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311.
Classifying Integrable Egoroff Hydrodynamic Chains 总被引:1,自引:0,他引:1
We introduce the notion of Egoroff hydrodynamic chains. We show how they are related to integrable (2+1)-dimensional equations of hydrodynamic type. We classify these equations in the simplest case. We find (2+1)-dimensional equations that are not just generalizations of the already known Khokhlov–Zabolotskaya and Boyer–Finley equations but are much more involved. These equations are parameterized by theta functions and by solutions of the Chazy equations. We obtain analogues of the dispersionless Hirota equations. 相似文献
312.
Christoph Hummel 《Proceedings of the American Mathematical Society》1998,126(8):2453-2458
We prove a result on certain finite index subgroups of rank one lattices which is motivated by cusp closing constructions.
313.
314.
Y. N. Ovchinnikov A. A. Varlamov 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,49(4):421-424
The effect of topological excitations in the form of small size (r ≪ξ(T))
vortex rings on thermodynamics of a bulk superconductor is considered. These
specific short wavelength fluctuations of the order parameter are analogous to
small vortex-antivortex pairs in superconducting film which were recently
studied in Y.N. Ovchinnikov, A.A. Varlamov, Phys. Rev. Lett. 94, 107007 (2004). The corresponding contribution to the free energy
below Tc is calculated. It is shown that fluctuations of this type give
the main temperature dependent contribution to the heat capacity of the
superconductor in the sufficiently large interval of temperatures below the
transition point. Important, that the sign of this contribution is opposite to
that one appearing due to the usual long wavelength fluctuation, leading to
smearing of the BCS jump of heat capacity. 相似文献
315.
We define and investigateCD
Σ,Γ(K, E)-type spaces, which generalizeCD
0-type Banach lattices introduced in [1]. We state that the space CD
Σ,Γ(K, E) can be represented as the space of E-valued continuous functions on the generalized Alexandroff Duplicate of K. As a corollary we obtain the main result of [6, 8]. 相似文献
316.
M. Salvato F. Bobba G. Calabrese C. Cirillo A. M. Cucolo A. De Santis A. Vecchione C. Attanasio 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,51(1):79-85
Resistivity vs. temperature measurements on
La0.7Ca0.3MnO3/YBa2Cu3O7-δ
/La0.7Ca0.3MnO3 (LCMO/YBCO/LCMO) trilayers with different
YBCO thickness, were performed in external magnetic field H up to 8 T. By
evaluating the activation energy U from the slope of the resistivity
Arrhenius plot, a strong depression of U has been observed when decreasing
the YBCO layer thickness and the absolute U values appear to be reduced with
respect to the values reported in literature in the case of YBCO thin films
and YBCO/insulating multilayers. Moreover, a logarithmic U vs. H dependence is
shown both in the case of thick and thin YBCO layers indicating the
formation of a two dimensional vortex lattice. The experimental data are
discussed considering the strong influence of the ferromagnetic LCMO on the
superconducting YBCO properties which reduces the effective YBCO thickness
more than predicted by the conventional theories. 相似文献
317.
针对地市建设有线数字电视统一服务平台的要求,对通过DS3接口传输、ATM over SDH,ASI接口传输,QAM调制等几种有线数字电视传输方法进行可行性探讨。 相似文献
318.
Bands in lattices of operators 总被引:1,自引:0,他引:1
C. B. Huijsmans A. W. Wickstead 《Proceedings of the American Mathematical Society》1996,124(12):3835-3841
We consider the lattice of regular operators on a Dedekind complete Banach lattice. We show that in general the projection onto a band generated by a lattice homomorphism need not be continuous and that the principal bands need not be closed for the operator norm. In fact it is possible to find a convergent sequence of operators all the members of which are disjoint from the limit.
319.
鉴于目前各地有线网络正在全面推广数字电视 ,掌握和推动数字电视的发展已十分重要。对有线数字系统的工作原理、系统各主要技术作分析 ,以便在实际工作中正确应用。 相似文献
320.
The flow behind a vibrating flexible cable at low Reynolds numbers can exhibit complex wake structures such as lace-like patterns,
vortex dislocations and frequency cells. These structures have been observed in experiments and numerical simulations, and
are predicted by a previously developed low-order coupled map lattice (CML). The discrete (in time and space) CML models consist
of a series of diffusively coupled circle map oscillators along the cable span. Motivated by a desire to modify the complex
wake patterns behind flexible vibrating cables we have studied the addition of control terms into the highly efficient CML
models and explored the resulting dynamics. Proportional, adaptive proportional and discontinuous non-linear (DNL) control
methods were used to derive the control laws. The first method employed occasional proportional feedback. The adaptive method
used spatio-temporal feedback control. The DNL method used a discontinuous feedback linearization procedure, and the controller
was designed for the resulting linearized system using eigenvalue assignment. These techniques were applied to a modeled vortex
dislocation structure in the wake of a vibrating cable in uniform freestream flow. Parallel shedding patterns were achieved
for a range of forcing frequency-forcing amplitude combinations studied to validate the control theory. The adaptive proportional
and DNL methods were found to be more effective than the proportional control method due to the incorporation of a spatially
varying feedback gain across the cylinder span. The DNL method was found to be the most efficient controller of the low-order
CML model. The required control level across the cable span was correlated to the 1/1 lock-on behavior of the temporal circle
map. 相似文献